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Sievers Pit M-77-098 SWSP, Oldcastle SW Group, Inc. Page 7 of 12 <br /> August 7, 2025 <br /> • Distance from the stream to the centroid of the dewatering trench (X) = 1,300 feet; <br /> and <br /> • Distance from the stream to the location of the parallel impermeable boundary = <br /> 2,500 feet from the stream. <br /> For the current submittal, a Unit Response Function (URF) was developed with the <br /> characteristic values given above and is provided in Appendix B. The lagged groundwater <br /> mining depletions for the proposed renewal are provided in Table 2. During the requested <br /> plan approval period, the annual lagged stream depletions from groundwater withdrawals <br /> are estimated to be 20.64 acre-feet per year, or 41.28 acre-feet for this SWSP approval <br /> period. <br /> The impact of surface water withdrawals, with an annual total of 10.44 acre-feet (7.13 <br /> acre-feet of evaporative losses from the 1.9-acre pond and 3.31 acre-feet for aggregate <br /> washing), is expected to be instantaneous. Therefore, the calculated total mining <br /> depletions annually during the proposed renewal period is 31.07 acre-feet per year, or <br /> 62.16 acre-feet for this SWSP period). <br /> Replacements <br /> Oldcastle will replace all lagged depletions created by expanded mining activity at the <br /> Sievers Pit during the worst-case downstream scenario for the Cameo Call, with the call <br /> period running from April through November of each year (Table 3), using a combination of <br /> consumptive use credit from the dry-up of irrigated lands of the Kaiser-Sievers Ditch as <br /> decreed in Case No. 83CW65 and a lease with WDWCD. <br /> Pursuant to Case No. 83CW65, a total of 22.1 acres of historically irrigated lands have been <br /> dried up as a result of the gravel mining operation, resulting in a consumptive use credit of <br /> 32.5 acre-feet during the May 5th through October 10th time period. These credits are not <br /> sufficient to replace the increased depletions from the Sievers Pit under this SWSP, therefore <br /> the remaining replacements will be provided by releases from WDWCD totaling 6.0 acre-feet <br /> per year (Table 3). These releases include a 10% transit loss. The Applicant currently has a <br />